In recent years, one content provision method has become main stream for supplying playback contents to consumer devices that are for playback of AV streams and typified by BD-ROM players. A playback content supplied according to the method includes an application program (hereinafter “application”) in addition to an AV stream in order to improve the interactivity.
Such a playback device is provided with a readable and writable recording medium, such as a hard disk, that is freely readable and writable by applications (hereinafter, “local storage”) and capable of storing the intermediate state of an application and settings of the device to the local storage. One example is directed to an application that executes a shooting game related to a content during playback of an AV stream, by presenting a screen overlaid on the AV playback screen. This application may store high scores of the game to the local storage. In another example directed to an application for allowing a user to register his/her favorite scenes, the application may store information indicating search points of a stream to the local storage.
Note that the capacity of a local storage differs depending on the manufacturer. Yet, it is commonly expected that the local storage will eventually run out of available space after the long-term use of the BD-ROM player and storing data piece after piece. One measure against the problem of an insufficient memory area is to provide a function of automatically erasing data with reference, for example, to information regarding the usage history of the user. Yet, this measure is not preferable because of the risk that data is erased against the user's intention.
Another measure is to provide a function of allowing the user to manually erase unnecessary data. In order to provide such a function of manually erasing data, it is then required to provide a method for presenting, to the user, the state of the storage area on the local storage in a manner that the user can specify a specific piece of data stored on the local storage.
One known method for displaying data stored in a storage area is disclosed in Patent Literature 1. According to the method disclosed in Patent Literature 1, each file is provided with file identification information embedded therein and the respective pieces of file identification information are displayed instead of their file names.    Patent Literature 1: JP Patent Application Publication No. 09-44387